THE AMERICAN BOTANIST 15 



less many other seeds that require considerable time to com- 

 plete their development even after they have fallen from the 

 parent plant and thus may fail to appear promptly when 

 planted. 



Grass Tubers. — Recently there were sent to the Depart- 

 ment of Agriculture in Washington, some curious subterran- 

 ean organs of a grass-plant which from the place of growth is 

 inferred to be the reed grass {Cinna arundinacea) . These 

 organs appear like small tubers with several constrictions 

 forming a necklace-like growth quite unlike anything known in 

 the grass family. An examination of the structure of these 

 objects shows that they consist of the shortened and greatly 

 enlarged basal joints of the stem, the constrictions being 

 formed by the modes. The specimens, although likened to 

 tubers are more properly regarded as corms, similar to those 

 of the crocus and gladiolus, but with constrictions that are 

 lacking in the more familiar plants. 



Plants in Dry Air. — One instinctively reasons that in 

 a warm climate almost any plant should be able to grow if 

 given sufficient moisture, but according to a writer in Plant 

 World there are other factors that may limit growth. In the 

 warmer parts of Arizona the extremely dry air may call upon 

 the plants for moisture faster than the roots can supply it and 

 in consequence the leaves wilt and become "fired" at the tips. 

 In the hottest parts of Arizona neither rhubarb nor horse- 

 radish will grow and the same is true of many of our common 

 plants including the dandelion and plantain. Even corn, which 

 farther north is reputed to love hot weather, fails to make a 

 crop in Arizona, though freely irrigated, if planted late enough 

 to be overtaken by the heated term with its dry air. Many 

 of the plants of more northern regions which cannot survive in 

 full sunlight grow very well in lath houses. The reason they 

 cannot stand the full sun is because their leaves are not pro- 



